Brown dwarfs, sometimes referred to as "failed stars," exist in a peculiar celestial zone between stars and planets. Although they are not large enough to burn like their larger stellar cousins, they are too heavy to be thought of as planets. Their distinguishing characteristic is their capacity for deuterium fusion. Deuterium is an isotope of hydrogen, and its synthesis releases energy, even though it does so at a considerably lower rate than the nuclear reactions that power true stars.

Due to their low temperatures, brown dwarfs frequently display a variety of colors, from deep red to cool brown or even black. Although some can occasionally glow with a faint luminosity, they never experience anything close to a star's dazzling radiance.

While distinguishing between a brown dwarf and a large planet can occasionally be difficult, there is a vital difference: mass. Brown dwarfs typically weigh between 13 times and 75–80 times that of Jupiter. Anything significantly smaller than this is generally considered a planet, while anything above it falls under the category of brown dwarfs.

Therefore, the object in question must first be weighed in order to determine whether it is a brown dwarf or a planet. Its mass will indicate whether it belongs in the brown dwarf category or the planetary realm.